The present disclosure relates to vehicle drive devices including a mechanical oil pump that is driven by a driving force source for wheels, an auxiliary oil pressure source, a driving force transmission mechanism that transmits a driving force between the driving force source and the wheels, and a case that contains at least the driving force transmission mechanism.
In recent years, an increasing number of vehicles that have an idle stop function to stop an internal combustion engine when the vehicle is stopped have been developed in order to reduce fuel consumption and exhaust gas emissions. Hybrid vehicles having both an internal combustion engine and a rotating electrical machine as driving force sources typically have a function to stop the internal combustion engine when the vehicle is decelerated in addition to when the vehicle is stopped. However, in vehicles having a hydraulically driven shift device, a mechanical oil pump that is driven by an internal combustion engine is also stopped when the internal combustion engine is stopped. In this case, oil supply to the shift device is stopped unless there is other oil pressure supplier. The shift device therefore may not be able to be appropriately operated. As a solution, a configuration is proposed which includes an electric oil pump as an auxiliary oil pressure source in addition to the mechanical oil pump so that oil discharged from the electric oil pump is supplied to the shift device when an internal combustion engine is stopped.
For example, Japanese Patent Application Publication No. 2010-236581 discloses a vehicle drive device having such a configuration. As is also disclosed in Japanese Patent Application Publication No. 2010-236581, the electric oil pump is typically attached to the outside of the case of the vehicle drive device. However, in the case where the electric oil pump is attached to the outside of the case of the vehicle drive device, it is necessary to provide dedicated oil passages for the electric oil pump which extend across the case to the outside of the case like a suction connection oil passage that supplies oil to the electric oil pump and a discharge connection oil passage that supplies oil discharged from the electric oil pump to the shift device etc. (a speed change mechanism). This complicates the overall oil passage configuration of the vehicle drive device.
The electric oil pump can be accommodated in the case of the vehicle drive device to simplify the overall oil passage configuration of the vehicle drive device. However, since the internal space of the case of the vehicle drive device is usually limited in size, squeezing the electric oil pump into the case of the vehicle drive device without taking into consideration the position of the electric oil pump in the case of the vehicle drive device can result in an increase in overall size of the device.
Japanese Patent Application Publication No. 2010-158975 discloses, as an example of a technique of simplifying oil passages of an electric oil pump and a mechanical oil pump, a technique of coupling a mechanical oil pump and an electric oil pump together by an oil passage formation block member having a common suction port and a common discharge port so as to provide a common oil passage for the mechanical oil pump and the electric oil pump. However, Japanese Patent Application Publication No. 2010-158975 does not take into consideration the position of the electric oil pump in the case of the vehicle drive device.